The use of biologically modified surfaces as active sensing regions for detection, identification, and sequencing of biological molecules is being intensively studied. In most sensors, selectivity is achieved by binding a known probe to the surface. The binding of the target molecules in the sample to the probe is detected by the generation of some physical or chemical signal. Several different read-out techniques, including optical, mass sensitive and electrochemical techniques are in present use. Many of these existing techniques require the use of fluorescent tags or other labels. The use of such fluorescent tags or other labels increases the complexity and cost of the detection techniques. Thus, there is significant interest in the development of sensor technologies that are label free. The use of electrical signals to sense biological binding events is particularly attractive because electrical measurements can be readily integrated with microprocessing and communication systems, potentially providing completely integrated sensing systems. Previous electrical detection systems have primarily focused on capacitance and/or electrochemical responses as the primary means of signal detection. It is desirable to miniaturize such detection systems to reduce costs and allow parallel processing, but as the physical size of the sensing region becomes smaller, employing current detection schemes which depend on measurements of changes in current can be difficult and unreliable, limiting the response time and sensitivity.